Download Physiology of Flight

Physiology of Flight
Know the physiology of flight.
1. State the layers of the atmosphere and the composition
of each.
2. Describe the physiological divisions of the flight
environment.
3. Define the physical laws of gases according to Boyle’s
Law, Dalton’s Law, and Henry’s Law.
Physiology of Flight
Know the physiology of flight.
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Describe the processes for respiration and circulation.
State the effects of reduced pressure at altitude.
Define spatial disorientation and motion sickness.
Describe individual stresses imposed upon a pilot
during flight.
Overview
1. Nature of the Atmosphere
2. Respiration and Circulation
3. Effects of Reduced Pressure at
Altitude
4. Rapid Decompression
5. Principles and Problems of Vision
Overview
6. Spatial Disorientation and Motion Sickness
7. Acceleration and Deceleration:
Increased G-Forces
8. Noise and Vibration
9. Heat and Cold During Flight
10. Noxious Gases and Vapors
11. Self-Imposed Stresses
Physiology of Flight
Nature of the Atmosphere
• Composition of the atmosphere
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78% nitrogen, 21% oxygen, 1% carbon dioxide.
Nitrogen is not used by body to support life.
Blood and other body fluids contain nitrogen.
Blood carries oxygen to all parts of the body.
Oxygen decreases at higher altitudes.
Nature of the Atmosphere
• Layers of the atmosphere
• Troposphere
• Most weather occurs in this
region
• Stratosphere
• Very little moisture
• Ionosphere
• Major characteristic-ionization
• Exosphere
• 600 to 1,200 miles above Earth
Physiological Divisions of the
Atmosphere
Nature of the Atmosphere
• Physiological Divisions
• Physiological zone
• Extends from sea level to 10,000 feet
• Physiological-deficient zone
• Extends from 10,000 to 50,000 feet
• Space-equivalent zone
• Extends from 50,000 feet to 120 miles above Earth
• Total space-equivalent zone
• Beyond 120 miles above Earth
Nature of the Atmosphere
• Physical Laws of Gases
• Boyle’s Law
• The volume of a gas is inversely proportional to its
pressure if the temperature remains constant.
• Dalton’s Law
• The total pressure of a mixture of gases is equal to the
sum of the partial pressure of each gas in that
mixture.
• Henry’s Law
• The amount of a gas in a solution varies directly with
the partial pressure that gas exerts on the solution.
Video
Respiration and Circulation
• Respiration is the exchange of oxygen and
carbon dioxide between an organism and its
environment.
• Closely related to circulation of blood
throughout the body.
Respiration and Circulation
• Decreasing oxygen pressure places stress on
the body affecting the respiratory system first.
• Made up of the lungs, bronchi and their small
branches, windpipe, mouth, and the nose.
• Air enters the nasal passages where it is warmed
and moistened and foreign matter removed.
Respiration and Circulation
Respiration and Circulation
• The amount of carbon dioxide in the blood
has an important effect on the action of the
heart.
• As carbon dioxide in the blood increases, the
heart rate speeds up so the heart can send more
oxygenated blood to the tissues.
• When carbon dioxide in the blood decreases,
the heart rate slows because tissues need less
oxygen.
Respiration and Circulation
• The respiratory system acts to keep the amount
of oxygen in the body tissues constant.
Video
Effects of Reduced Pressure at
Altitude
• As the body goes to high altitude it must
make adjustments to the reduced atmospheric
pressure in order to keep the body tissue
constant. If the pressure outside the body is
greatly reduced and the body is not
adequately protected, it cannot make the
necessary adjustments.
Effects of Reduced Pressure at
Altitude
• Hypoxia - a deficiency of oxygen in the body
cells or tissue.
• Most frequently the result of decreased pressure
on an unprotected body.
• In flight is usually caused by an insufficient
amount of oxygen in the inhaled air.
• Greatest danger when pilot becomes engrossed in
duties and doesn’t notice the first symptoms.
Video
Effects of Reduced Pressure at
Altitude
• Hyperventilation
• A person affected by hypoxia tends to increase
breathing rate in an attempt to take in more
oxygen.
• May result from great emotional tension or
anxiety.
Video
Effects of Reduced Pressure at
Altitude
• Trapped Gases-Ear Block
Effects of Reduced Pressure at
Altitude
• Trapped Gases-Sinus Block
Effects of Reduced Pressure at
Altitude
• Trapped Gases-Tooth Pain
• Untreated cavities where pulp is exposed may be
the cause of tooth pain at altitude.
• The toothache often disappears at the same
altitude that if was first observed on ascent.
• Gases may be trapped in the teeth at altitude in
abscesses.
Effects of Reduced Pressure at
Altitude
• Trapped Gases-Stomach and Intestines
• In flights above 25,000 feet the expanding gases
may cause severe pain, lowering blood pressure
and eventually shock.
• Usually air that has been swallowed.
• When barometric pressure falls the partial
pressures of the gases in the body fluids decrease.
• The escaping gases cause decompression
sickness.
Video
Effects of Reduced Pressure at
Altitude
• The Bends
• Release of nitrogen into
the joints of the body.
Effects of Reduced Pressure at
Altitude
• The Chokes
• Another form of decompression sickness.
• Deep, sharp pains under the sternum.
• Increased expansion of the lungs causes the pain
to increase.
Effects of Reduced Pressure at
Altitude
• Skin Symptoms
• Type of decompression sickness that involves
sensations of the skin.
• Small bubbles of nitrogen under the skin produce
itching, hot and cold feelings and tingling.
• The rash does not disappear with descent and may
last for hours.
Effects of Reduced Pressure at
Altitude
• Treatment of Decompression Sickness
• As decompression sickness becomes more severe,
the pain caused by escaping gas bubbles becomes
more intense.
• As symptoms appear in flight, 100% oxygen
should be administered.
• If symptoms still exist after landing, compression
therapy will be administered at the nearest
hyperbaric facility.
Video
Rapid Decompression
• Rapid decompression at a high altitude brings
on an explosion as the pressure suddenly
decreases.
• At 63,000 feet or above body fluids boil if
exposed to the ambient atmosphere.
• The time of useful consciousness may be
reduced by 60% if the decompression is rapid
and the air is forced out of the lungs due to
rapid expansion.
Video
Principles and Problems of
Vision
Spatial Disorientation and
Motion Sickness
• Spatial disorientation - the inability to
accurately orient yourself with respect to the
Earth’s horizon.
• We use four sensory systems to maintain our
orientation and equilibrium (balance).
Spatial Disorientation and
Motion Sickness
• The Visual System
• Eyes provide the strongest and most reliable
orientation information during flight.
• When the horizon is not correct, your vestibular
disorientation disappears; you may still
experience visual illusions caused by false
horizon.
Spatial Disorientation and
Motion Sickness
• The Vestibular System
Spatial Disorientation and
Motion Sickness
• The Vestibular System
Spatial Disorientation and
Motion Sickness
• The Somatosensory System
• Consists of tactile pressure receptors in the skin,
muscles, tendons and joints.
• Often called the “seat-of-the-pants” sense.
Video
Acceleration and Deceleration:
Increased G-Forces
• When military flight crews perform
maneuvers or when astronauts are launched or
recovered they may be subjected to severe
stress from the effects of acceleration and
deceleration.
• The stresses are felt as increases in weight or
gravity forces (G-Forces).
Acceleration and Deceleration:
Increased G-Forces
Noise and Vibration
• Cause flyers more inconvenience than any
other factor in flight.
• Sound intensity or loudness is measured in
decibels.
• Vibrations are measured in frequency.
• One effect of vibration is blurred vision.
Heat and Cold During Flight
• The largest amount of heat is generated on the
skin of aircraft and spacecraft as it travels at
high speeds through the atmosphere.
• An aircraft flying at Mach 2 has skin
temperatures increased by about 400o F as a
result of aerodynamic heating.
• There are two dangers associated with
exposure of the body to cold.
Noxious Gases and Vapors
• Inside an enclosed cabin, noxious gases and
vapors may accumulate.
• The breathing atmosphere can easily become
contaminated from inside sources if care is
not taken.
• Carbon Monoxide.
Self-Imposed Stresses
• Alcohol
• One drink at 10,000 feet can have the same effect
as two or three drinks at sea level.
• Tobacco
• Smoking at 10,000 feet produces effects
equivalent to those experienced at 14,000 feet
without smoking.
• Drugs
• Aspirin, nasal decongestants, tranquilizers or
sedatives.
Video
Fit for Flight
Summary
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4.
5.
6.
Nature of the Atmosphere
Respiration and Circulation
Effects of Reduced Pressure at Altitude
Rapid Decompression
Principles and Problems of Vision
Spatial Disorientation and Motion Sickness
Summary
7. Acceleration and Deceleration: Increased
G-Forces
8. Noise and Vibration
9. Heat and Cold During Flight
10. Noxious Gases and Vapors
11. Self-Imposed Stresses